Improvement in modes of making corundum-wheels



Y UNITED STATES PATENT OFFICE.

A. W. CAI.DER, OF SAN FRANCISCO, CALIFORNIA.

IMPROVEMENT IN MODES OF MAKING COEUNDUM-WI-IEELS.

. Specification forming part of Letters Patent No. 93,413, dated August 10, 1869.

To all 'whom it may concern Bc it known that I, A. W. CALDER, of the city and county of San Francisco, State of center hole, grooved for the purpose of screwing said wheel A upon the arbor or mandrel of the lathe or revolving shaft used for the purpose of revolving the wheel.

What I claim as my invention, and desire to secure byLetters Patent for the same, is

The metallic center placed in the cornndnm or emery wheel, in the manner and for the-purposes substantially as above set forth.

A. W. OALDER.

Witnesses A. IG. WATEEHOUSE, MICHAEL MEAGHER. 

